Potassium (k) blood test

A blood test to check potassium is done to:

• Check levels in people being treated with medicines such as diuretics and for people having kidney dialysis.
• Check to see whether treatment for too low or too high potassium levels is working.
• Check people with high blood pressure who may have a problem with their kidneys or adrenal glands.
• Check the effects of extra nutrition (total parenteral nutrition [TPN]) on potassium levels.
• Check to see whether certain cancer treatments are causing too many cells to be destroyed (cell lysis). Cell lysis syndrome causes very high levels of some electrolytes, including potassium.

A health professional uses a needle to take a blood sample, usually from the arm.

In general, there's nothing you have to do before this test, unless your doctor tells you to.

Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.

Many conditions can affect potassium levels. Blood potassium levels also vary with age. Your doctor will talk with you about any abnormal results that may be related to your symptoms and past health.

High values

• High blood potassium levels may be caused by damage or injury to the kidneys. This prevents the kidneys from removing potassium from the blood normally.
• High blood potassium levels can also be caused by conditions that move potassium from the body's cells into the blood. These conditions include crushing injuries and heart attack.
• Taking too many potassium supplements can also cause high levels of potassium in the blood.
• Too much acid (pH) in the blood makes potassium levels higher by causing the potassium in the body's cells to "leak" out of cells and into the blood.
• Some medicines, such as aldosterone antagonists and angiotensin-converting enzyme (ACE) inhibitors, can cause high potassium levels.

Low values

• Low blood potassium levels can be caused by high levels of aldosterone (hyperaldosteronism) made by the adrenal glands.
• Other conditions that can cause low blood potassium levels include severe burns, cystic fibrosis, alcohol use disorder, Cushing's syndrome, malnutrition, vomiting, diarrhea, and certain kidney diseases, such as Bartter's syndrome. Bartter's syndrome is a condition characterized by enlargement of certain kidney cells. It is more common in children and may be linked to an abnormally short stature (dwarfism). The cause of Bartter's syndrome is not fully known.
• Medicines, such as diuretics, are a common cause of low potassium levels.